In order to solve the problem of particle contamination on the surface of optical elements, on the basis of single laser dry cleaning, laser cleaning assisted by air displacement system was proposed. Nd∶YAG laser with 355nm wavelength was used. Typical SiO2 pollutant particulate with optical surface diameter of 1μm~50μm for sol-gel SiO2 thin film fused silica was theoretically analyzed and cleaning experiments were carried out. The process parameters for laser cleaning were obtained. The results show that, for single crystal laser dry cleaning of sol-gel membrane fused silica samples, optimum laser energy density is 2.29J/cm2. The process parameters of laser cleaning are different from those of uncoated quartz. Under the optimum technological parameters, the effect of single laser cleaning on SiO2 particles with particle size more than 1μm is obvious. The removal rate is 82.96%. Excessive contamination density will weaken the cleaning effect and damage the base. Laser cleaning assisted by air displacement system can further enhance the removal effect of particle contamination on optical surface. This research has important research significance and practical value for on-line cleaning of optical components and the design of cleaning equipment in large-scale high-power solid-state laser devices.